45 is not good if you have a vinyl pool, even if your CYA is over 100. It might bleach your liner, if the measure is correct.

Try mixing 1/4 cup of pool water with 3/4 c of distilled water (Steam distilled is sold at most supermarkets and it's cheap) and see if you get around 10ppm

You may want to leave it open to the sun, or drain some water and add some.

But mostly you need to start by confirming that number.

It WILL come down if you just leave it open to the sun. There is a chlorine neutralizer available (It's in the PS232 to PS234 and TFP test kits, but just a few drops), but I don't know about its usage in pools.